1. Field of the Invention
The present invention pertains to the field of portable computing devices. More particularly, the present invention pertains to conditioning a battery in a computing device while external power is applied.
2. Description of Related Art
Conditioning a battery typically prolongs the life of the battery and may also allow a battery charge sensor to calibrate itself. The first step of conditioning a battery is ensuring that the battery discharges completely or at least discharges to a certain level. Such discharging should be followed by charging until the battery is fully charged, or at least close to fully charged. Conditioning avoids cycling the battery only through a small charge-discharge range and reduces the likelihood that the battery will be limited in charge range by its "memory" of previous cycles.
Even though some batteries purportedly do not have this "memory" effect, conditioning may still be important. A "smart" battery designed for use with a computer system may include a sensor circuit to determine battery information, such as the amount of remaining charge. After many charge and discharge cycles, the battery sensor may lose its calibration and need to be calibrated again. Calibration may be accomplished by conditioning the battery. In other words, calibration may be accomplished by discharging the battery to a first (e.g., minimum) known level and then recharging the battery to a second (e.g., maximum) known level.
Unfortunately, prior art portable computing devices do not automatically condition batteries. Battery conditioning involves discharging the battery, and prior art devices do not discharge the battery when external power (e.g., direct current power from an A/C adapter plug or an alternate external direct current source) is applied. In fact, prior art devices often charge the battery any time that external power is applied and the battery is less than fully charged.
Consequently, to discharge the battery, the user of a prior art portable computing device may need to operate the device without external power until the battery is discharged. Alternatively, the user could simply leave the system inactive, presumably eventually discharging the battery. Both of these methods may be inconvenient to users since users may not be able to schedule computer use to accommodate battery charging and discharging.
Thus, with prior art systems, conditioning batteries requires user intervention. Such user intervention is inconvenient and reduces the likelihood that users will condition their batteries regularly to preserve battery charge range and allow accurate battery readings. Consequently, the prior art does not provide an adequate solution which automatically conditions batteries.